Salesforce.com has debuted a free version of its Chatter social networking application for businesses in what CEO Marc Benioff described as an effort to expand customer use of the software throughout their organizations.

"Our goal is very simple. How can we get everyone on Chatter?" Benioff said in a keynote speech Tuesday at Salesforce's Dreamforce conference in San Francisco. He said Chatter Free went live this past weekend and he encouraged the IT managers among the estimated 14,500 keynote attendees to turn the service on.

The Chatter Free edition is essentially a stripped down version of the commercial Chatter social networking software that debuted at Dreamforce last year and went live in June.

Based on the same kind of social invitation model used by Facebook, Chatter Free allows a user of Salesforce's applications to invite co-workers, even those who aren't Salesforce users, to collaborate using Chatter. Chatter Free's capabilities include profiles, status updates, real-time feeds, file sharing, groups, filters and invitations.

Salesforce also has mobile versions of Chatter that run on Research in Motion's BlackBerry devices and Apple's iPad and IPhone systems, and a version for Google Android devices is under development. And in February Salesforce will launch Chatter.com, a service that Benioff described as intended to compete with "discrete social networking startups."

More than 60,000 of Salesforce's 87,700 customers are now using Chatter. Salesforce turns the Chatter service on at no extra charge for users of the company's CRM and Force.com services and charges $15 per user, per month to expand Chatter to users within customer organizations who don't use Salesforce apps.

Salesforce has not disclosed how much revenue Chatter is generating through such fees. But Benioff has declared the product to be strategic because it expands Salesforce's presence within customer companies and reduces customer attrition rates.

Benioff said customers are adopting Chatter as a replacement for older technologies such as IBM's Lotus Notes. Benioff took a dig at the aging product when, in mentioning Facebook founder and CEO Mark Zuckerberg, he said: "Lotus Notes was conceived before Mark Zuckerberg."

Wednesday Salesforce is widely expected to unveil a new release of the Force.com platform for developing and deploying cloud applications.